1. Field of the Invention
Fluorination of perhydro carbon containing materials is achieved under mild temperature conditions to yield useful perfluoro derivatives. More specifically, perhydro organic compounds and organic cations are converted to their perfluoro relatives by treatment with thermodynamically unstable fluorine containing compounds (such as NiF.sub.3 and NiF.sub.4) and fluorine containing salts (such as salts containing NiF.sub.6.sup.2-).
2. Description of the Background Art
An important industrial process for the conversion of organic precursors to fully fluorinated derivatives (perfluoro carbon compounds) is the Simons Process. The Simons Process (J. H. Simons, J. Electrochem. Soc., 95, 1949, 47; J. H., Simons, H. T. Francis and J. A. Hogg, ibid., 95, 1949, 53; J. H. Simons and W. J. Harland, ibid., 95, 1949, 55; J. H. Simons, W. H. Pearlson, T. J. Briace, W. A. Wilson and R. D. Dresdner, ibid., 95, 1949, 59; J. H. Simons and R. D. Dresdner, ibid., 95, 1949, 64, J. H. Simons (ed.), in Fluorine Chemistry, Vol. 1, Academic, New York, 1950, p. 414; J. H. Simons and T. J. Brice, ibid., Vol. 2, 1954, p. 333, J. Burdon and J. C. Tatlow, Adv. Fluorine Chem., 1, 1960, 129, and S. Nagase, Fluorine Chem. Rev., 1, 1967, 77, all of which are herein incorporated by reference) uses an electrochemical cell to oxidize perhydro-organic materials, at a nickel anode, to their perfluoro-relatives. The electrolyte for that process is liquid anhydrous hydrogen fluoride (aHF) in which sodium fluoride, or other fluorobases, are dissolved (the latter, to provide for electrical conductance).
Thus, at this time, the bulk of perfluoro-organic materials (other than perfluoro-polymers such as Teflon) are made by adaptions of the Simons electrochemical fluorination (ECF) process in which organic compounds are electrochemically oxidized and fluorinated at a nickel anode in aHF, made conducting with a weak base.
Subject Applicants have demonstrated (N. Bartlett, R. D. Chambers, A. J. Roche R. C. H. Spink, L. Chacon, and J. M. Whalen, Chem. Commun., 1996, 1049, which is herein incorporated by reference) that the Simons Process chemistry could be conveniently simulated at room temperature, and often in high efficiency using nickel trifluoride (NiF.sub.3), nickel tetrafluoride (NiF.sub.4) or hexafluoronickelate(IV) salts. The thermodynamically unstable fluorides, NiF.sub.3 and NiF.sub.4, were first established by Applicant Bartlett and his collaborators (B. Zemva, K. Lutar, L. Chacon, M. Fele-Beuermann, J., Allman, C. Shen, and N. Bartlett, J. Am. Chem. Soc., 117, 1995, 10025, Which is herein incorporated by reference), the precursor from which both are derived being the commercially available salt potassium hexafluoronickelate (IV), K.sub.2 NiF.sub.6. The latter is prepared by an adaption of the original synthesis of Klemm and Huss (W. Klemm, and E. Huss, Z. anorg. Chem., 258, 1949, 221, which is herein incorporated by reference), in which nickel (II) chloride and potassium fluoride are heated in a nickel bomb with fluorine gas under pressure (several atmos.) at 275.degree. C.
Fluorocarbon compounds can often be derived from hydrocarbon precursors by well controlled interaction of the latter with elemental fluorine, as pioneered by Margrave and Lagow, (J. L. Margrave and R. J. Lagow, Prog. Inorg. Chem., 26, 1979, 161, and references therein, which are herein incorporated by reference) and Lagow and his co-workers. (R. J. Lagow, T. R. Bierschenk, T. J. Juhlke, and H. Kawa, in Synthetic Fluorine Chemistry, ed. G. A. Olah, R. D. Chambers, and G. K. S. Prakash, J. Wiley, New York, 1972, ch. 5, p. 97 and references therein, which are herein incorporated by reference). This previous method also requires precise control of F.sub.2 gas pressures and substrate concentrations. Although the convenient reagent cobalt trifluoride, CoF.sub.3, is less potent than elemental fluorine, it has long been employed in the synthesis of highly fluorinated organic compounds (M. Stacey and J. C. Tatlow, Adv. Fluorine Chem., 1060, 1, 166 and references cited therein; R. E. Banks and J. C. Tatlow, Fluorine, the First Hundred Years, ed. R. E. Banks, D. W. A Sharpe and J. C. Tatlow, Elsevier, 1986, p. 267, 337, and references cited therein, both of which are herein incorporated by reference). Nevertheless, high temperatures are necessary for the process, depending on the substrate, and this has often resulted in unwanted carbon-carbon bond cleavage. The use of the subject NiF.sub.3, NiF.sub.4 or NiF.sub.6.sup.2- species provides for easy control of the fluorination process, as in the Simons Process, but without the awkward experimental aspects of the latter. Those awkward aspects arise from the requirement, that the substrate to be fluorinated, has to be carried effectively to the surface of a nickel anode of the electrochemical cell, and the products separated from the effluent gases, which have come from that anode.
It is noted that the conversion of NiF.sub.2 to NiF.sub.6.sup.2- has been previously achieved at ordinary temperatures but only with the exotic reagent krypton difluoride (A. Jesih, K. Lutar, I. Leban, and B. Zemva, Inorg. Chem., 28, 1989, 2911, which is herein incorporated by reference), which is itself a costly material to prepare, and dangerous to use (because of its thermodynamic instability) in quantities of more than a few grams. The novel subject method provides an effective conversion of NiF.sub.2 to NiF.sub.6.sup.2- which uses no more than one atmosphere pressure of elemental fluorine, and temperature of 0.degree. C. to room temperature. Since NiF.sub.2 is insoluble in aHF, and the NiF.sub.6.sup.2- salts of the alkalis are all soluble, the latter are readily separated from the former.
It is further noted that presently NiF.sub.6.sup.2- salts are made by adaptions of the original synthesis (W. Klemm, and E. Huss, Z. anorg. Chem., 258, 1949, 221) of Klemm and Huss. For small scale high purity synthesis of more exotic salts such as (XeF.sub.5).sub.2 NiF.sub.6, krypton difluoride has been used (A. Jesih, K. Lutar, I. Leban, and B. Zemva, Inorg. Chem., 28, 1989, 2911). the former synthesis is inefficient with NiF.sub.2 as the nickel reagent, the latter is costly, and, on a large scale, potentially dangerous. Neither synthesis competes in effectiveness with that described here for NiF.sub.6.sup.2- salt synthesis from NiF.sub.2.
It is additionally noted, therefore, that anyone currently wishing to convert NiF.sub.2 to NiF.sub.6.sup.2- salts would use either the thermal method of Klemm and Huss (W. Klemm, and E. Huss, Z. anorg. Chem., 258, 1949, 221) or resort to using krypton difluoride (A. Jesih, K. Lutar, I. Leban, and B. Zemva, Inorg. Chem., 28, 1989, 2911). The former method is not effective for the synthesis of Li.sub.2 NiF.sub.6, and the other alkali salts would be highly impure unless the mixture of NiF.sub.2 and alkali fluoride was reground and refired several times. The synthesis of krypton difluoride and the handling of that reagent is only practiced in a limited number of laboratories world-wide, whereas the subject process described here for NiF.sub.2 conversion to NiF.sub.6.sup.2-, could be readily adopted by any laboratory accustomed to the handling of aHF and F.sub.2.
The foregoing information reflects the state of the art of which the applicant is aware. in relation to the subject invention, and is tendered with the view toward discharging applicant's acknowledged duty of candor in disclosing information which may be pertinent in the examination of this application. It is respectfully submitted, however, that any disclosed, non-subject matter information does not teach or render obvious applicant's claimed invention.